Ryan Droney,¹ Amanda Goh^1,2

¹QML Pathology, ²Faculty of Medicine, The University of Queensland

A 70 year old male with a previously treated plasma cell myeloma presented with a borderline macrocytic anaemia, thrombocytopenia and marked leukocytosis (61.7x10⁹/L) with neutrophilia (53.1x10⁹/L). Peripheral blood examination revealed mild rouleaux with toxic granulation and Dohle bodies in his neutrophils.

Bone marrow examination revealed marked hypercellularity, expanded granulopoiesis and reduced erythropoiesis (Myeloid:Erythroid ratio 7.3:1). Megakaryopoiesis was normal. There was no dysplasia in any lineage. These findings suggested a myeloproliferative neoplasm, such as Chronic Neutrophilic Leukaemia (CNL).

There was a mild plasmacytosis (6%) with moderate atypia, and a low level plasma cell population on flow cytometry without clear clonality. Myeloma FISH detected a deletion of the IGH locus, as previously reported in this patient. 

Regarding the leukocytosis, JAK2 Val617Phe and BCR::ABL1 testing was negative. Myeloid NGS revealed two clonal variants in TET2 and DNMT3A at low VAF (3-4%).

Leukaemoid reactions associated with plasma cell dyscrasias are rare and hypothesised to arise from granulocyte colony-stimulating factor (G-CSF) production by clonal plasma cells.¹ Neutrophilia has been considered as an indicator of disease status,² although the prognostic implications of presenting with a leukaemoid reaction is not fully known. Co-occurrence of a plasma cell dyscrasia and CNL is described,³ however no CSF3R mutation was detected. 

The submission of this work was the original idea and primary work of Dr Ryan Droney. The abstract and poster was created with the assistance of Dr Amanda Goh.

References

^1. Xie W, Xu J. Neutrophilic leukemoid reaction associated with plasma cell neoplasm mimicking chronic neutrophilic leukemia. Blood. 2019 Jan 10;133(2):182. doi: 10.1182/blood-2018-10-881532. PMID: 30630849.

^2. Milojkovic D, Hunter A, Barton L, Cross NC, Bain BJ. Neutrophilic leukemoid reaction in multiple myeloma. Am J Hematol. 2015 Nov;90(11):1090. doi: 10.1002/ajh.24106. PMID: 26147944.

^3. World Health Organization. (2022). WHO classification of tumours: Haematolymphoid tumours.